MOBILE PHONE ARCHITECTURE & TECHNOLOGY

HISTORY

The idea of the first cellular network was brainstormed in 1947

Disadvantages All the analogue system suffered from

overload Incompatibility & proprietary nature Roaming was not possible

GSM/group special mobile started out as the name of working group of CEPT( European conference of Postal & telecommunication)

Task of this group was standardisation of digital mobile communication

GSM had become the name of standard itself. The acronym GSM had been changed from

Group Spécial Mobile to Global Systems Mobile Telecommunications.

Technology

GSM (global system mobile) CDMA (Code division multiple access)

Architecture of GSM network

SD

Mobile Station

BTS

MSC/VLR

SIM MEBSC

Base StationSubsystem

GMSC

Network Subsystem

AUCEIR HLR

Other Networks

Note: Interfaces have been omitted for clarity purposes.

+

PSTN

PLMN

Internet

Cellular Systems The geographic

area is divided into cells

Each cell has a Base Station managing the communications

A set of cells managed by a single MSC is called Location Area

Base Station

VLRMSC

VLR MSC

HLR

MSC Mobile Switching Center

VLR Visitor Location Register

HLR Home Location Register

land link

land link

Radio link

Mobile Station (MS) Mobile Equipment

International Mobile Equipment Identity (IMEI) number

Subscriber Identity Module (SIM) Personal Identification Number (PIN) International Mobile Subscriber Identity

(IMSI) number Enables access to subscribed services Smart card

MOBILE SWITCHING CENTER

MSC is a sophisticated telephone exchange which provides

circuit-switched calling mobility management GSM services to the mobile phones roaming

within the area that it serves. ie voice, data and fax services, as well as SMS and call divert.

Tasks of the MSC include delivering calls to subscribers as they arrive based on

information from the VLR connecting outgoing calls to other mobile subscribers

or the PSTN. delivering SMS from subscribers to the SMSC and vice

versa arranging handovers from BSC to BSC carrying out handovers from this MSC to another supporting supplementary services such as

conference calls or call hold. collecting billing information.

BASE STATION SUB-SYSTEM BSS consists of two nodes

Base Transceiver station (BTS)-: BTS contains the equipment for transmitting and receiving of radio signals (transceivers), antennas, and equipment for encrypting and decrypting communications with the Base Station Controller (BSC)

Base Station Controller (BSC)

Provides classically, the intelligence behind the BTS’s

It handles allocation of radio channels, receives measurements from the mobile phones, controls handovers from BTS to BTS

DATA BASES

H.L.R (HOME LOCATION REGISTER)

V.L.R (VISITOR LOCATION REGISTER)

E.I.R (EQUIPMENT IDENTIFY REGISTER)

HLR

Master subscriber database Used for the management of mobile

subscriber Contains subscription levels, call

restrictions, supplementary services and most recent location of the subscriber

VLR

Temporary subscriber data base Contains data needed by the MSC for

servicing visiting subscribers Contains information for all visiting

mobile subscribers

EIR

Database which contains information about the mobile equipment identity

Used for equipment security and validation of different types of mobile equipment

FREQUENCY RANGE

MODE TX FREQUENCY RX FREQUENCY

GSM 900 890-915 MHz 935-960 MHz

DCS 1800 1710-1785 MHz 1805-1880 MHZ

PCS 1900 1850-1910 MHz 1930-1990 MHz

ACCESS SCHEMES

CDMA BASICS CDMA (Code Division Multiple Access) splits calls

into fragments and send them over different frequencies simultaneously

The use of multiple frequencies gives CDMA effective protection against interference and lost calls

CDMA supports true packet switching and does not use time slots, therefore is more bandwidth efficient than TDMA -- also a more direct path to 3G

Current CDMA penetration in the world market is about 27%

ADVANTAGES OF CDMA

Voice quality Call security Network capacity Call maintenance

BLOCK DIAGRAM

MAJOR SECTIONS

There are three major sections inside a mobile phone

Power Section Radio Section Computer Section

POWER SECTION A Power section deals with power related

tasks such as power distribution or charging the battery so this section is divided into two sub sections

Power distribution Charging section

RADIO SECTION A radio section has basically a set of four

main functions-:

Band Switching

RF Power Amplification

Transmitter

Receiver

COMPUTER SECTION

A computer section consists of two main functions

CPU (central processing unit) Memory (RAM,FLASH,COMBO CHIP)

TRANSMISSION

AUDIO IC RF IC

VCO

TX COUPLER POWER AMPLIFIER

MODULATION

MIC

ANTENNA SWITCH

PCB LAYOUT

NOKIA 2600